This is a simple project showing you how to make a digital voltmeter using Arduino where the readings are displayed in a Liquid Crystal Display LCD20x4.

The proposed voltmeter design can read up to 50V. We are using analogue to digital conversion process.

Arduino microcontroller equipped with 10-bit analogue to digital converter (ADC). This means Arduino can read 2^10=1024 discrete voltage levels.In this project, we measure the input voltage range between 0 to 50V by using the voltage divider. It is very simple to use Arduino as a voltmeter. Arduino UNO has 5 analog pin to read the input analog value. The circuit consists of two resistors, one LCD display and an Arduino which is brain of the digital voltmeter. The two resistor acts as voltage divider, the node of the divider is connected to analogue pin # A0 of the Arduino, which reads the input voltage. Ground connection is established between Arduino and external voltage source.

You cannot feed 50V directly to a Arduino I/O pin, you need a resistor divider network that converts 0-50V range into 0-5V.A 5.1V Zener diode in the figure is to prevent V_AN0 (V in) to rise above 5.1V if the input voltage goes much above 50V. This will protect the Arduino board.

The Arduino in built 10 bit ADC,can be used for measuring the 0Volt to 50 Volts Digital Voltmeter. LCD display connected with Arduino Uno will be used for displaying the measured voltage. This voltmeter can read only DC voltage.

Code Designing in Arduino IDE 1.8.0 :

So, here’s the programming code youneed to use for Displaying voltage value on LCD using Arduino board in Proteus ISIS: